DEMYELINATION IN MULTIPLE SCLEROSIS

我们研究的长期目标是了解生物化学和 免疫介导的脱髓鞘发生的分子过程 多发性硬化症和格林巴利综合征等疾病。 我们有 以前我们的研究集中在脱髓鞘诱导的病理生物学 由补体，尤指膜反应性末端补体 复合物（TCC）。 上一个资助期的实验结果 我们发现髓磷脂通过直接C1激活补体， 结合，并允许TCC形成，这是脱髓鞘所需的， 髓鞘形成培养物。 TCC可引起髓鞘分裂， 髓鞘囊泡形成，因为结构髓鞘的有效水解 TCC可通过激活髓鞘来诱导MBP等蛋白质的表达 蛋白酶 在少突胶质细胞（OLG）中，TCC动员花生四烯酸 (AA)LTB4 此外，发现亚溶解性TCC选择性地减少 编码蛋白脂质和MBP（但不编码β-肌动蛋白）的mRNA积累。 在转录抑制剂的存在下也观察到这种TCC效应， 表明mRNA加速衰变。 因此，髓鞘形成，一个重要的 OLG的功能，可受补体的影响。 在本申请中，我们将研究AA动员的机制， 探索信号信使需要激活脂肪酶负责 AA由TCC生产。 髓鞘吞噬作用的效率 由补体衍生的调理肽C3 b和 iC 3b将进行评估。 我们发现髓磷脂缺乏髓鞘， 下调补体级联的蛋白质。 因此， C3 b和iC 3b对髓鞘的调理作用将增强巨噬细胞介导的 通过与补体相互作用损伤和清除髓鞘 受体CR 1和CR 3在巨噬细胞上表达。 此外，分子 髓鞘蛋白转录后调控机制 将研究TCC的基因。 RNA序列特异性基序 这是负责加速mRNA衰变，在响应 TCC引起的信号，将被识别。 最后， 免疫介导的脱髓鞘中的补体系统将在 vivo. 具体地说，在体内直接通过髓鞘激活C1的作用 将检查血脑屏障的破坏以及 TCC在炎性脱髓鞘中的作用。

The long term goal of our research is to understand the biochemical and molecular process underlying immune mediated demyelination occurring in diseases such as multiple sclerosis and Guillain Barre syndrome. We have previously focused our studies on pathobiology of demyelination induced by complement, especially the membrane-reactive terminal complement complexes (TCC). Experimental results during the preceding grant period are summarised; We found that myelin activates complement by direct C1 binding, and allows TCC to form, which is required for demyelination of myelinating cultures. The TCC may cause splitting myelin lamellae and myelin vesiculation, since effective hydrolysis of structural myelin proteins such as MBP can be induced by TCC through activation of myelin proteases. In oligodendrocytes (OLG), TCC mobilizes arachidonic acid (AA) and LTB4. In addition, sublytic TCC was found to selectively reduce the MRNA accumulation encoding proteolipid and MBP (but not beta-actin). This TCC effect was also seen in the presence of transcription inhibitor, indicating accelerated MRNA decay. Thus, myelin formation, an important function of OLG, can be affected by complement. In this application, we will study the mechanisms of AA mobilization by exploring signal messengers required to activate lipases responsible for AA production by TCC. The efficiency of myelin phagocytosis by macrophages mediated by complement-derived opsonic peptides, C3b and iC3b, will be evaluated. We found that myelin is devoid of DAF, membrane protein which down-regulates complement cascade. Therefore, increased opsonization of myelin by C3b and iC3b will enhance macrophage-mediated damage and clearance of myelin through interaction with complement receptors, CR1 and CR3, expressed on macrophages. In addition, molecular mechanisms involving post-transcriptional regulation of myelin protein genes by TCC will be investigated. The RNA Sequence-specific motif(s) which is responsible for the accelerated MRNA decay, in responds to the signal induced by TCC, will be identified. Finally, the role of the complement system in immune-mediated demyelination will be examined in vivo. Specifically, the role of C1 activation directly by myelin in vivo following breakdown of blood brain barrier will be examined as well as the role of TCC in inflammatory demyelination.